1. Field of the Invention
The present invention generally relates to the storage and disposal of sharp medical instruments such as contaminated hypodermic needles, and more specifically to a safety cap and instrument hub.
2. Description of the Related Art
Hypodermic needles are used to give injections and draw blood from patients. These needles can become contaminated with any number of infectious and potentially lethal diseases. Other medical instruments such as scalpels can become similarly contaminated. The threat of accidental puncture wounds from contaminated needles or scalpels poses a significant safety risk to medical personnel, hospital cleaning staff, waste disposal workers and the general public.
Until the early 1980's, it was standard practice to "recap" a needle after use. This required the user to grasp the narrow plastic sleeve in one hand, and with the other hand insert the contaminated needle into the sleeve. These sleeves were designed primarily to provide physical protection for the needle and to maintain sterility before use. Because of the sleeve's size and shape, a user could very easily miss the sleeve and puncture his or her hand. Furthermore, the cap could be accidentally or intentionally removed, thereby exposing the contaminated needle.
The medical community recognized this danger and adopted a policy against recapping. Instead, medical treatment areas are supposed to be equipped with special "sharps containers" for disposing contaminated sharp objects such as hypodermic needles or scalpels. These containers are typically fitted with either flexible plastic flaps or fixed baffles over their openings. The flaps are formed from a plastic diaphragm which has a hole at its center with slits extending radially outward from the hole. These designs are supposed to allow contaminated objects to be pushed through the opening, but prevent them from falling back out of the container. As a practical matter, sharps containers cannot be provided immediately adjacent every location where injections are being given, blood is being drawn or incisions are being made. Therefore, the user must carry the exposed contaminated needle or scalpel some distance before disposing of it. Furthermore, the sharp instruments have managed to back out of the container's opening or poke through its walls, posing a significant safety risk.
U.S. Pat. No. 4,883,470, "Safety Cap", discloses a flared cap for storing the needle and cannula hub before and after use. The cap and cannula hub have complementary rib designs which allow a syringe to both engage the hub and remove the needle from the cap prior to use, and to reinsert the contaminated needle into the cap and disengage the syringe. The flared cap reduces the risk of self-puncture, but the user must still grasp the cap with his off hand to recap the needle. Furthermore, the recapped contaminated needle can be withdrawn from the cap by reengaging a syringe.
U.S. Pat. Nos. 4,846,811, 4,874,384, 5,342,309 and 5,053,018 disclose slidable or telescoping sleeves that fit over the syringe. The sleeves are retracted to expose the needle, and then slid down and locked to shield the tip. These syringes are awkward to use due to the extra bulk on the syringe itself. Furthermore, the incorporation of moveable parts increases the cost and reduces the reliability; moving parts break.